If your kit didn't include tar paper, I have a roll of roof underlayment you can have. It's leftover from my roof replacement. I don't know much about it, but it seems much more substantial than typical tar or felt roofing paper. It's not enough to do your entire roof, but certainly enough for the ridge. I think it's similar to this:
http://www.homedepot.com/p/Owens-Cor...AA10/205664211